What is Cosmology? - Elementary Particle Physics Group
What is Cosmology? - Elementary Particle Physics Group What is Cosmology? - Elementary Particle Physics Group
Weighing Neutrinos with Cosmology “What exactly are they doing…?” arXiv:0911.5291 - PRL Shaun Thomas: UCL Birmingham Seminar: 2nd Feb 2011
- Page 2 and 3: Outline 1. ‘The Cosmological Mode
- Page 4 and 5: Neutrino oscillations indicate they
- Page 6 and 7: What is Cosmology? • Study of the
- Page 8 and 9: The Cosmological Model The statisti
- Page 10 and 11: Signatures in the Model • Suppres
- Page 12 and 13: Signatures in the Model • Suppres
- Page 14 and 15: Probes of Cosmology Supernovae (SN)
- Page 16 and 17: Probes of Cosmology + Galaxy Cluste
- Page 18 and 19: Probes of Cosmology + Galaxy Cluste
- Page 20 and 21: Cosmology and Neutrinos Komatsu et
- Page 22 and 23: The Dark Energy Survey (DES) http:/
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- Page 26 and 27: Determining the neutrino mass is im
- Page 29: The Photometric Redshift “photo-z
Weighing Neutrinos with <strong>Cosmology</strong><br />
“<strong>What</strong> exactly are they doing…?”<br />
arXiv:0911.5291 - PRL<br />
Shaun Thomas: UCL Birmingham Seminar: 2nd Feb 2011
Outline<br />
1. ‘The Cosmological Model’<br />
2. Neutrino signatures in the model<br />
3. Probes of the Model<br />
• Cosmic Microwave Background<br />
• Galaxy Surveys<br />
• Supernovae and Baryon Oscillations<br />
4. Current/Previous work: Thomas, Abdalla & Lahav: [arXiv:0911.5291] - PRL<br />
5. For the Future…?<br />
Shaun Thomas: UCL Birmingham Seminar: 2nd Feb 2011
Determining the neutrino mass <strong>is</strong> important because:<br />
OR - “things to put in funding applications….”<br />
1. Neutrinos’ mass has a significant impact on cosmological measurements<br />
_<br />
2. Incorrect neutrino mass will bias cutting edge science: dark energy<br />
_<br />
3. <strong>Particle</strong> physics - cosmology compar<strong>is</strong>on: unique check on all cosmology!<br />
- -<br />
1. Neutrinos’ mass has a significant impact on cosmological measurements<br />
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -<br />
-<br />
• Extension to the standard model and intrinsic nature etc.<br />
-<br />
• (Neutrinos: 3 Nobel Prizes over the last quarter of a century or so!!)<br />
Shaun Thomas: UCL<br />
Birmingham Seminar: 2nd Feb 2011
Neutrino oscillations indicate they have mass!<br />
A cosmolog<strong>is</strong>t’s understanding..<br />
But not on the absolute scale of mass…<br />
• Beta-decay kinematics<br />
• Neutrinoless double beta-decay<br />
• <strong>Cosmology</strong>!<br />
For example…<br />
KATRIN<br />
nemo<br />
ST, Abdalla, Lahav (2009)<br />
Age of prec<strong>is</strong>ion <strong>Cosmology</strong><br />
Not just interesting<br />
An integral part of the cosmological model…<br />
Shaun Thomas: UCL Birmingham Seminar: 2nd Feb 2011
Neutrino oscillations indicate they have mass!<br />
A cosmolog<strong>is</strong>t’s understanding..<br />
But not on the absolute scale of mass…<br />
• Beta-decay kinematics<br />
• Neutrinoless double beta-decay<br />
For example…<br />
KATRIN<br />
nemo<br />
• <strong>Cosmology</strong>!<br />
Age of prec<strong>is</strong>ion <strong>Cosmology</strong><br />
Shaun Thomas: UCL<br />
ST, Abdalla, Lahav (2009)<br />
http://www-ik.fzk.de/~katrin/index.html<br />
Not just interesting<br />
An integral part of the cosmological model…<br />
Birmingham Seminar: 2nd Feb 2011
<strong>What</strong> <strong>is</strong> <strong>Cosmology</strong>?<br />
• Study of the Universe on the largest scales<br />
• Asks: <strong>What</strong> <strong>is</strong> the Origin, evolution and fate of the Universe?<br />
• Take a census of the Universe’s contents<br />
“In science there <strong>is</strong> only physics; all the<br />
rest <strong>is</strong> stamp collecting“, Rutherford<br />
BUT:<br />
Interesting contents!<br />
Themes intimately related<br />
Shaun Thomas: UCL<br />
Birmingham Seminar: 2nd Feb 2011
Famously, supernovae indicated Dark Energy<br />
Probe of d<strong>is</strong>tance and expansion: The smooth Universe<br />
E.g., Perlmutter et al. (1999)<br />
<strong>Cosmology</strong><br />
Combination of probes, data and surveys<br />
Probes of an<strong>is</strong>otropy: The clumpy Universe!<br />
APM survey: Efstathiou et al. (1990)<br />
Shaun Thomas: UCL Birmingham Seminar: 2nd Feb 2011
The Cosmological Model<br />
The stat<strong>is</strong>tic <strong>is</strong> the ‘Power Spectrum’<br />
Does NOT predict the exact location<br />
of a galaxy or structure in the sky<br />
Does predict the stat<strong>is</strong>tical d<strong>is</strong>tribution<br />
of galaxies or structures in the sky<br />
The power spectrum tells us how much some field varies on different scales<br />
Parameters go into the cosmological model - detailing physical quantities (e.g.<br />
neutrinos or dark energy) - that change the power spectrum -> compare to data<br />
Shaun Thomas: UCL Birmingham Seminar: 2nd Feb 2011
The Power Spectrum<br />
“Variance of the underlying stat<strong>is</strong>tic as<br />
a function of scale”<br />
Power spectrum of people at a party<br />
• People cluster into speaking groups -<br />
separated by ~ metre<br />
power spectrum<br />
• Different groups separated by several<br />
metres<br />
• Romantically involved might be closer…<br />
1 2 3 4<br />
Scale (metres)<br />
Shaun Thomas: UCL Birmingham Seminar: 2nd Feb 2011
Signatures in the Model<br />
• Suppress the growth of matter structure and cosmological perturbations<br />
Neutrinos have large thermal<br />
velocities and Free-stream out of<br />
over-densities/inhomogeneities<br />
thus suppressing the clustering of<br />
matter and galaxies<br />
Shaun Thomas: UCL Birmingham Seminar: 2nd Feb 2011
Signatures in the Model<br />
• Suppress the growth of matter structure and cosmological perturbations<br />
Dark Matter N-body simulations<br />
0 eV Neutrinos 1 eV Neutrinos<br />
Which we see in the power spectrum…<br />
Shaun Thomas: UCL Birmingham Seminar: 2nd Feb 2011
Signatures in the Model<br />
• Suppress the growth of matter structure and cosmological perturbations<br />
Smaller Scales<br />
Galaxy tracers = Galaxy Survey<br />
Shaun Thomas: UCL Birmingham Seminar: 2nd Feb 2011
Probes of <strong>Cosmology</strong><br />
Cosmic Microwave Background (CMB)<br />
E.g. WMAP and Planck<br />
Model Data Constraint<br />
Parameter degeneracy - constrain matter component<br />
=> better neutrino determination<br />
WMAP 5 year (CMB) : < 1.3 eV (95% CL)<br />
Komatsu et al. [arXiv:0803.0547]<br />
Thomas et al. [arXiv:0911.5291]<br />
Shaun Thomas: UCL Birmingham Seminar: 2nd Feb 2011
Probes of <strong>Cosmology</strong><br />
Supernovae (SN)<br />
E.g. Supernova Legacy Survey<br />
Standard candle allows one to measure the expansion h<strong>is</strong>tory<br />
Th<strong>is</strong> <strong>is</strong> sensitive to matter content of the Universe<br />
Baryon Acoustic Oscillations (BAOs)<br />
Primordial CMB photon-baryon oscillations are imprinted<br />
onto late-time matter power spectrum: BAO<br />
Standard ruler allows one to measure the expansion h<strong>is</strong>tory<br />
Th<strong>is</strong> <strong>is</strong> sensitive to matter content of the Universe<br />
CMB + SN + BAO : < 0.69 eV<br />
(95% CL)<br />
Thomas et al. [arXiv:0911.5291]<br />
Shaun Thomas: UCL Birmingham Seminar: 2nd Feb 2011
Probes of <strong>Cosmology</strong><br />
+ Galaxy Clustering! Sloan Digital Sky Survey (SDSS)<br />
• Suppress the growth of matter structure and cosmological perturbations<br />
Smaller Scales<br />
Shaun Thomas: UCL Birmingham Seminar: 2nd Feb 2011
Probes of <strong>Cosmology</strong><br />
+ Galaxy Clustering! Sloan Digital Sky Survey (SDSS)<br />
Luminous Red Galaxies (LRGs)<br />
MegaZ: Largest galaxy survey<br />
723,556 LRGs<br />
7,746 square degrees<br />
• Luminous - can map out over Universe<br />
• Accurate redshift/d<strong>is</strong>tance information<br />
Thomas, Abdalla & Lahav - MNRAS (2010)<br />
0.45 < z < 0.65<br />
Four redshift bins<br />
Shaun Thomas: UCL Birmingham Seminar: 2nd Feb 2011
Probes of <strong>Cosmology</strong><br />
+ Galaxy Clustering! Sloan Digital Sky Survey (SDSS)<br />
723,556 LRGs<br />
Luminous Red Galaxies (LRGS)<br />
7,746 square degrees<br />
0.45 < z < 0.65<br />
12 Parameters:<br />
! b<br />
h 2 ;! c<br />
h 2 ;! "<br />
;#;n s<br />
;ln(10 10 A s<br />
); m $<br />
;A SZ<br />
;b 1<br />
;b 2<br />
;b 3<br />
;b 4<br />
Shaun Thomas: UCL<br />
%<br />
CMB + SN + BAO + SDSS LRGs + HST: < 0.28 eV (95% CL)<br />
Thomas et al. [arXiv:0911.5291]<br />
Birmingham Seminar: 2nd Feb 2011
Probes of <strong>Cosmology</strong><br />
+ Galaxy Clustering! Sloan Digital Sky Survey (SDSS)<br />
723,556 LRGs<br />
Luminous Red Galaxies (LRGS)<br />
7,746 square degrees<br />
0.45 < z < 0.65<br />
12 Parameters:<br />
! b<br />
h 2 ;! c<br />
h 2 ;! "<br />
;#;n s<br />
;ln(10 10 A s<br />
); m $<br />
;A SZ<br />
;b 1<br />
;b 2<br />
;b 3<br />
;b 4<br />
Shaun Thomas: UCL<br />
%<br />
CMB + SN + BAO + SDSS LRGs + HST: < 0.28 eV (95% CL)<br />
Thomas et al. [arXiv:0911.5291]<br />
Birmingham Seminar: 2nd Feb 2011
Stat<strong>is</strong>tics in <strong>Cosmology</strong><br />
Bayes<br />
• Marginal<strong>is</strong>ed over the other parameters<br />
• Limit <strong>is</strong> irrespective of the other parameters<br />
• Limit accounts for uncertainty in other parameters<br />
12 Parameters:<br />
! b<br />
h 2 ;! c<br />
h 2 ;! "<br />
;#;n s<br />
;ln(10 10 A s<br />
); m $<br />
;A SZ<br />
;b 1<br />
;b 2<br />
;b 3<br />
;b 4<br />
Shaun Thomas: UCL<br />
%<br />
Birmingham Seminar: 2nd Feb 2011
<strong>Cosmology</strong> and Neutrinos<br />
Komatsu et al. [arXiv:0803.0547]<br />
< 0.67 eV (CMB+SN+BAO)<br />
Tereno et al. [arXiv:0810.0555] < 0.54 eV (CMB+SN+BAO+WL)<br />
Ichiki, Takada & Takahashi [arXiv:0810.4921] < 0.54 eV (CMB+SN+BAO+WL)<br />
Seljak et al. [arXiv:0604335] < 0.17 eV (+ Lyman Alpha…)<br />
Systematics - e.g. winds?<br />
Thomas, Abdalla & Lahav [0911.5291]<br />
0.28 eV<br />
CMB + SN + BAO + SDSS LRGs +HST<br />
<strong>Cosmology</strong> <strong>is</strong> starting to predict that experiments such as KATRIN will not detect anything<br />
UNIQUE opportunity for cons<strong>is</strong>tency check!!!!!<br />
Shaun Thomas: UCL Birmingham Seminar: 2nd Feb 2011
Systematics<br />
We have seen that ‘prec<strong>is</strong>ion’ cosmology <strong>is</strong> sensitive to the neutrino<br />
mass and that we are in the process of making very good constraints<br />
However<br />
Although we want tighter neutrino constraints<br />
We also want trustworthy neutrino constraints.<br />
Galaxy Bias<br />
Model underlying matter<br />
power spectrum but measure<br />
the galaxy power spectrum<br />
How are they related?<br />
Non-linearities<br />
Bias result or lose data<br />
Perturbation theory/<br />
N-body simulations<br />
Parameter Degeneracies<br />
Degeneracy with w increases<br />
error bar<br />
L_max = 300 =><br />
L_max = 200 =><br />
0.28 eV<br />
0.34 eV<br />
Shaun Thomas: UCL<br />
Birmingham Seminar: 2nd Feb 2011
The Dark Energy Survey (DES)<br />
http://www.darkenergysurvey.org<br />
Blanco 4m Telescope - Cerro Tololo Inter-American Observatory (CTIO)<br />
5000 sq. deg around the southern galactic cap<br />
525 nights: Oct - Feb (2011-2016)<br />
Shaun Thomas: UCL<br />
Birmingham Seminar: 2nd Feb 2011
The Dark Energy Survey (DES)<br />
http://www.darkenergysurvey.org<br />
Measure Dark Energy with 4 main techniques:<br />
1. Clusters<br />
2. Galaxy Clustering<br />
3. Weak Lensing<br />
4. Supernovae<br />
Also give exqu<strong>is</strong>ite information on:<br />
Neutrino masses, gravity etc….<br />
Shaun Thomas: UCL<br />
Birmingham Seminar: 2nd Feb 2011
In the Future…<br />
The Dark Energy Survey (DES)<br />
http://www.darkenergysurvey.org<br />
• 300 million galaxies<br />
• UCL central involvement<br />
• Data taking October 2011<br />
Forecast for Galaxy Clustering + Planck: < 0.12 eV<br />
E.g. Lahav, Kiakotou, Abdalla and Blake - arXiv: 0910.4714<br />
• Plus other future surveys will start to impinge on hierarchy<br />
• Unique cons<strong>is</strong>tency test for cosmology - are we doing it right?<br />
Shaun Thomas: UCL<br />
Birmingham Seminar: 2nd Feb 2011
Summary<br />
• <strong>Cosmology</strong> <strong>is</strong> a sensitive neutrino experiment! (Funded billions of years ago!)<br />
• Massive neutrinos suppress the growth of structure<br />
• Probes such as galaxy clustering are sensitive to th<strong>is</strong> growth<br />
• It <strong>is</strong> an integral part of cosmological model and parameter space<br />
• Have a complete complementary constraint (sub eV region)<br />
Having produced data for a tighter constraint<br />
• The Future: Constraints with more and improved data<br />
• The Future: Understanding systematics!!!!<br />
Tighter neutrino constraint. Trustworthy neutrino constraint.<br />
Shaun Thomas: UCL Birmingham Seminar: 2nd Feb 2011
Determining the neutrino mass <strong>is</strong> important because:<br />
OR - “things to put in funding applications….”<br />
1. Neutrinos’ mass has a significant impact on cosmological measurements<br />
_<br />
2. Incorrect neutrino mass will bias cutting edge science: dark energy<br />
_<br />
3. <strong>Particle</strong> physics - cosmology compar<strong>is</strong>on: unique check on all cosmology!<br />
- -<br />
1. Neutrinos’ mass has a significant impact on cosmological measurements<br />
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -<br />
-<br />
• Extension to the standard model and intrinsic nature etc.<br />
-<br />
• (Neutrinos: 3 Nobel Prizes over the last quarter of a century or so!!)<br />
Shaun Thomas: UCL<br />
Birmingham Seminar: 2nd Feb 2011
Related and Further Reading<br />
<strong>Cosmology</strong> and Neutrinos<br />
ST, Abdalla & Lahav [arXiv:0911.5291]<br />
Komatsu et al. [arXiv:0803.0547]<br />
Elgaroy and Lahav [arXiv:0606007]<br />
Seljak et al. [arXiv:0604335]<br />
Agarwal & Feldman [arxiv:0812.3149]<br />
Galaxy Clustering<br />
ST, Abdalla & Lahav [arxiv:1011.2448]<br />
ST, Abdalla & Lahav [arxiv:1012.2272]<br />
Neutrino Experiments<br />
MINOS<br />
NEMO<br />
KATRIN Contact: sat@star.ucl.ac.uk<br />
Shaun Thomas: UCL Birmingham Seminar: 2nd Feb 2011
The Photometric Redshift<br />
“photo-z”<br />
Observe the flux through broad filters<br />
• Template<br />
For example:<br />
# SDSS<br />
# Le Phare<br />
• Empirical<br />
Use training set<br />
# Polynomial Fitting<br />
# Neural Network<br />
Padmanabhan et al. 2007<br />
ANNz - Coll<strong>is</strong>ter & Lahav (2004)<br />
Shaun Thomas: UCL<br />
Birmingham Seminar: 2nd Feb 2011
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